How did movement between the Nazca Plate and South American Plate cause the Chile earthquake of 2010?

The 2010 Chile earthquake was caused by the ongoing subduction of the Nazca Plate beneath the South American Plate.1

The earthquake occurred when a 300- to 375-mile (500- to 600-km) stretch of the fault separating these two plates ruptured. This event was driven by the convergence of the plates, which created immense stress that caused rocks along the boundary to shatter. Research suggests that the buildup of water pressure between the plates may have acted as a catalyst for this rupture.2

The force of this subduction process had significant physical consequences: it forced a portion of the seabed upward, which displaced the water above and triggered a tsunami. Additionally, the powerful energy released by the subducting plate was sufficient to shift Earth’s axis, shortening the length of a day by more than a microsecond.2